Tipler published a paper on how to build a time machine, a Tipler Cylinder, back in 1974. This machine would enable you to travel back in time.

We're going to use this imaginary train to get as close as possible to the speed of light and see how it becomes a time machine. On board are passengers with a one-way ticket to the future.

Tipler published a paper on how to build a time machine, a Tipler Cylinder, back in 1974. This machine would enable you to travel back in time.

Tipler published a paper on how to build a time machine, a Tipler Cylinder, back in 1974. This machine would enable you to travel back in time.

Astrophysicist Ron Mallett believes he's figured out how to build a time machine that would allow someone to travel to the past.

In other words, it could help scientists know whether time travel is possible, and if we could use any protocol to build a time machine.

Travelling in time might sound like fantasy, but some physicists think it might really be possible.

Tipler published a paper on how to build a time machine, a Tipler Cylinder, back in 1974. This machine would enable you to travel back in time.